diff options
| author | Roland Stigge <stigge@antcom.de> | 2011-02-10 15:01:23 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2011-02-11 16:12:20 -0800 |
| commit | 6e20fb18054c179d7e64c0af43d855b9310a3394 (patch) | |
| tree | 7fe6eda33162dbeab61afc2392229b9c57a644f1 | |
| parent | 01e05e9a90b8f4c3997ae0537e87720eb475e532 (diff) | |
drivers/gpio/pca953x.c: add a mutex to fix race condition
Add a mutex to register communication and handling. Without the mutex,
GPIOs didn't switch as expected when toggled in a fast sequence of
status changes of multiple outputs.
Signed-off-by: Roland Stigge <stigge@antcom.de>
Acked-by: Eric Miao <eric.y.miao@gmail.com>
Cc: Grant Likely <grant.likely@secretlab.ca>
Cc: Marc Zyngier <maz@misterjones.org>
Cc: Ben Gardner <bgardner@wabtec.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
| -rw-r--r-- | drivers/gpio/pca953x.c | 28 |
1 files changed, 22 insertions, 6 deletions
diff --git a/drivers/gpio/pca953x.c b/drivers/gpio/pca953x.c index a261972f603..b473429eee7 100644 --- a/drivers/gpio/pca953x.c +++ b/drivers/gpio/pca953x.c @@ -60,6 +60,7 @@ struct pca953x_chip { unsigned gpio_start; uint16_t reg_output; uint16_t reg_direction; + struct mutex i2c_lock; #ifdef CONFIG_GPIO_PCA953X_IRQ struct mutex irq_lock; @@ -119,13 +120,17 @@ static int pca953x_gpio_direction_input(struct gpio_chip *gc, unsigned off) chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); reg_val = chip->reg_direction | (1u << off); ret = pca953x_write_reg(chip, PCA953X_DIRECTION, reg_val); if (ret) - return ret; + goto exit; chip->reg_direction = reg_val; - return 0; + ret = 0; +exit: + mutex_unlock(&chip->i2c_lock); + return ret; } static int pca953x_gpio_direction_output(struct gpio_chip *gc, @@ -137,6 +142,7 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc, chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); /* set output level */ if (val) reg_val = chip->reg_output | (1u << off); @@ -145,7 +151,7 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc, ret = pca953x_write_reg(chip, PCA953X_OUTPUT, reg_val); if (ret) - return ret; + goto exit; chip->reg_output = reg_val; @@ -153,10 +159,13 @@ static int pca953x_gpio_direction_output(struct gpio_chip *gc, reg_val = chip->reg_direction & ~(1u << off); ret = pca953x_write_reg(chip, PCA953X_DIRECTION, reg_val); if (ret) - return ret; + goto exit; chip->reg_direction = reg_val; - return 0; + ret = 0; +exit: + mutex_unlock(&chip->i2c_lock); + return ret; } static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off) @@ -167,7 +176,9 @@ static int pca953x_gpio_get_value(struct gpio_chip *gc, unsigned off) chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); ret = pca953x_read_reg(chip, PCA953X_INPUT, ®_val); + mutex_unlock(&chip->i2c_lock); if (ret < 0) { /* NOTE: diagnostic already emitted; that's all we should * do unless gpio_*_value_cansleep() calls become different @@ -187,6 +198,7 @@ static void pca953x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val) chip = container_of(gc, struct pca953x_chip, gpio_chip); + mutex_lock(&chip->i2c_lock); if (val) reg_val = chip->reg_output | (1u << off); else @@ -194,9 +206,11 @@ static void pca953x_gpio_set_value(struct gpio_chip *gc, unsigned off, int val) ret = pca953x_write_reg(chip, PCA953X_OUTPUT, reg_val); if (ret) - return; + goto exit; chip->reg_output = reg_val; +exit: + mutex_unlock(&chip->i2c_lock); } static void pca953x_setup_gpio(struct pca953x_chip *chip, int gpios) @@ -517,6 +531,8 @@ static int __devinit pca953x_probe(struct i2c_client *client, chip->names = pdata->names; + mutex_init(&chip->i2c_lock); + /* initialize cached registers from their original values. * we can't share this chip with another i2c master. */ |